.cart {
  margin: 15px;
  border: 1px solid transparent;
  box-shadow: 0 0 30px -15px blue;
}

.item {
  display: flex;
  margin: 15px;
  border: 1px solid #ddd;
  line-height: 50px;
}

.ordinal {
  flex-basis: 10%;
}
.name {
  flex-basis: 40%;
}
.price {
  flex-basis: 10%;
}

/* 首先 .amount 是 .item 容器内部的一个 弹性项目( flex item ) */
.amount {
  flex-basis: 20%;
  align-self: center;
  /* 其次 .amount 也是一个 弹性容器 ( flex container ) */
  display: inline-flex;
  border: 1px solid blue;
  height: 30px;
  background: blue;
  line-height: 30px;
  text-align: center;
}

.amount>i {
  flex-basis: 20%;
  color: #fff;
  user-select: none;
}

.amount>b {
  flex-basis: 60%;
  background: #fff;
}

.subtotal {
  flex-basis: 10%;
}
.operation {
  flex-basis: 10%;
}
.operation > i {
  padding: 5px;
  cursor: pointer;
  background: #00f;
  color: #fff;
  font-style: normal;
  user-select: none;
}
